Mycobacterium kansasii disease was diagnosed in an 85-year-old woman admitted to the hospital for cough and gradually worsening breathlessness. Transbronchial biopsy indicated either non-necrotizing granulomata or bronchiolitis obliterans organizing pneumonia (BOOP). She was cured with combined therapy of specific anti-mycobacterial medications and systemic steroids. To our knowledge, this is the first report of M. kansasii non-tuberculous mycobacterium disease with a BOOP-like pattern on lung biopsy.